Recently, optical semiconductor devices, including semiconductor lighting devices, such as, for example, single or multi-color LEDs, and sensing devices, such as, for example, various kinds of image sensors are increasingly incorporated in mass-market consumer products, such as mobile phones, computers, automobiles etc. In order to fulfill the very severe demands on cost, size, and reliability required for any component to be included in such products, much effort has been spent in the development of optical semiconductor devices. In particular, development of a package for an optical semiconductor element comprised in such an optical semiconductor device is an important area of development. It is also expected that packaging costs, for various kinds of optical semiconductor devices, will become dominant with respect to cost.
Due to the essential requirement of optical interaction with the surroundings inherent for optical semiconductor devices, standard electronics packaging techniques can typically not be used for such optical semiconductor devices. For example, an optical element, such as a lens or a diffuser typically needs to be accurately positioned with respect to the optical semiconductor element (for example, light-source or sensor) comprised in the optical semiconductor device. Furthermore, the optical semiconductor device should be made such that it can withstand various environmental conditions, such as, for example, temperature cycling without losing functionality.
In WO 2004/023522 a light emitting die package is disclosed, which, referring to FIG. 1, includes a substrate 1, a reflector plate 2 and a lens 3. After having mounted a light-emitting diode (LED) assembly 4 on the substrate 1, the reflector plate 2 is bonded on the substrate 1 so that it surrounds the LED assembly 4. The reflector plate has a ledge 5 for supporting the lens 3. After having bonded the reflector plate 2 to the substrate, the LED assembly 4 is encapsulated by a soft encapsulation material, and thereafter the lens 3 is positioned on the ledge 5 and adheres to the encapsulation material.
Although providing means for positioning a lens relative to a LED assembly, the optical semiconductor device package disclosed in WO 2004/023522 does not appear suited for mass production of very compact and cost-efficient optical semiconductor devices. It also appears cumbersome to connect to a circuit board due to its large footprint and awkwardly located connector pads.
Accordingly, there is a need for an improved optical semiconductor device, and, in particular for a more compact and less costly optical semiconductor device.